Not Applicable.
Not Applicable.
A cantilevered lifting truck (counterweighted fork-lift truck) proves to be a universal equipment for the transport and handling of palletized unit loads. It is provided with a combustion-engine or battery-electric drive and may also be moved outdoors on an uneven terrain, which depends on the tires chosen. The power required to operate industrial trucks requires to be carried along by the vehicle. The power is stored in the fuel tank if combustion-engine operated lifting trucks are used and in a battery if battery-electric industrial trucks are used. The latter has to be recharged for a period of at least eight hours after the end of a shift. If the lifting truck is employed during several successive shifts the discharged battery requires to be exchanged against a freshly charged one after the end of each shift.
Since the battery mostly is centrally installed in the vehicle and its positioning is important for the vehicle""s static stability and, hence, the usability of the industrial truck the exchange it needs necessitates great expenditure. Particularly for vehicles having a driver""s cab as is frequently encountered for this vehicle type, some manipulations are necessary to perform the exchange. In addition, the overhead guard for the driver has to be designed so as to enable the battery to be removed by means of a hoisting gear. A difficulty in employing counterweighted lifting trucks of a known type is the so-called residual load-bearing capacity, i.e. the maximum ultimate load admissible depending on the lifting level. It decreases more and more with an increase in the lifting level for reasons of static stability, which reduces the economy in vehicle use, particularly in those cases where large loads require to be lifted to large levels. Moreover, if the driver carries out stacking operations at high levels his sight conditions will worsen, which has an adverse effect on the safety in operation, working speed, and physical stresses acting on the driver.
In battery-electrically operated fork-lift trucks, it is known to laterally push the battery out of the vehicle""s chassis. For this purpose, the vehicle""s chassis has to be of an appropriate construction and there has to be a stationary device onto which to shift the battery when it leaves the vehicle. The large lateral opening detracts from the frame structure of the vehicle.
It is further known to tilt the driver""s seat module including the overhead guard for the driver, which covers the battery, to the rear for the maintenance of the battery and its exchange. This approach is comparable to a tiltable driver""s cab on a lorry. Since the pivot is very much off the centre a relatively large force is necessary to tilt the driver""s seat module and to keep it in the opened position. Therefore, the tilting operation mostly requires an extra driving mechanism. Furthermore, any objects not secured in the cab will fall out or fall into disorder during the tilting operation.
To enhance the residual load-bearing capacity, industrial trucks have become known in which the load-bearing axle is displaced to the front when the load is lifted with the inclination of the inclinable lift frame remaining unchanged. In this approach, the load-bearing axle which is generally under a heavy load requires to be displaced if static stability is intended to be enhanced, which presupposes an appropriate design of the load-bearing axle and its drive. Another approach to this problem, which is disclosed in DE 198 15 121 A1, provides a displaceable counterweight which, if required, may be displaced to the rear towards the vehicle""s rear end along with the rear steering axle. In this embodiment, the wheelbase of the vehicle will vary during the displacing operation, which causes a misalignment of the steering geometry and a concomitant wear of the tires.
To improve the sight conditions while doing stacking at large lifting levels, industrial trucks have become known in which the driver""s seat and possibly the driver""s seat module is inclined to the rear while the load is being lifted and, thus, to improve the sight to the load at large lifting levels. This also requires a separate drive, which will be activated according to the respective lifting level.
It is the object of the invention to provide a battery-electrically operated industrial truck, particularly a counterweighted lifting truck, wherein the accessibility of the battery is optimized.
In the invention, the basic body has a space open to the top to receive the battery. The reception space is preferably between the vehicle""s axles. However, such reception spaces are known as such. According to the invention, the driver""s seat assembly is arranged on a lid-like cover which is displaceably guided in an approximately horizontal fashion or even in an inclined fashion at the upper side of the basic body to selectively unblock the reception space. However, a drive is required if the arrangement is inclined.
The cover, along with the driver""s seat assembly, may be displaced to the rear for the maintenance of the battery or a battery exchange. This makes the battery freely accessible from the top and, for example, may be simply removed by means of a hoisting gear from the vehicle towards the top. It is understood that if the upper side of the vehicle""s basic body is configured in such a way the power and signal lines leading from the driver""s seat assembly to the individual operating functions are made sufficiently long and flexible in order that a displacement of the driver""s seat assembly relative to the basic body may readily take place such that line interruptions will not occur.
Various possible ways are imaginable in guiding the cover on the basic body. Thus, for example, a pure guideway may be provided using rails or the like. As an alternatively, according to an embodiment of the invention, there is an interaction of rollers on the cover or the basic body or rails on the basic body or the cover to obtain an easy-to-perform relative motion between the cover and the basic body. If possible, the motion should be such that it does not require a separate drive to make the battery reception space freely accessible.
To cause the cover to be safely held in the final positions, an embodiment of the invention provides that it be locked via locking means in the final positions. It is understood that the locking means are unlockable in an appropriate manner.
However, it is also imaginable to provide a separate drive for displacing the cover. This is mainly the case if it is desired that the residual load-bearing capacity be enhanced by displacing the cover to the rear. An aspect of the invention provides that sensors are provided for the weight of the load and/or the position of the load centre of gravity and/or the inclination of the lift frame and/or the lifting level of the load-bearing means, and that a control device for the driving mechanism controls the position of the cover in response to at least one of the sensor signals. This allows to displace the vehicle centre of gravity of the industrial truck by displacing the cover towards the steering axle, thus enhancing the static stability of the industrial truck in the longitudinal direction of the vehicle. A safe operation of the vehicle is possible if this displacement is combined with the maximum admissible travelling speed. For example, if a heavy load needs to be lifted to a very high level the driver will position the vehicle, for example, in front of a rack and will vertically place the inclinable lift frame. Subsequently, the lifting motion will begin and, starting from a certain lifting level which is reached, will automatically cause the cover to be displaced towards the vehicle""s rear end until a maximum rear final position is reached. The space required therefor will also result from the operational width necessary for four-wheeled vehicles if there are close space conditions. For reasons of safety, the back of the cover may be provided with an appropriate sensor which detects obstacles or even persons opposing the pushing motion and will stop the pushing motion automatically as soon as an obstacle appears.
The invention involves a series of advantages. It allows an optimum accessibility of the battery for a maintenance and exchange. The displaceable cover enhances the residual load-bearing capacity of a counterweighted lifting truck and, hence, the economy of its use. The economy of the industrial truck is enhanced as well since it is extremely easy to exchange its battery. It also enhances the driver""s sight when he performs stacking operations at large lifting levels and, hence, the vehicle""s safety in operation when the cover is displaced towards the vehicle""s rear end.